Focused ultrasonic beams operating in the 500 kHz to MHz frequency range have been shown to preserve their spatial and temporal character when transmitted through adult human skulls. This circumstance has been proven both in vitro and in vivo. These facts, along with signal processing and image enhancement schemes, will be used to design and construct a clinical ultrasonic system for the diagnosis of intracranial disease. After preliminary physical model and experimental animal studies, a clinical program will be conducted. This clinical program will involve intercomparison and evaluation studies to compare the efficacy of the ultrasonic method with existing neuroradiological procedures including CAT scanning.